新型高耐磨性贝氏体铸钢的研究

研究了新型贝氏铸钢的组织,力学性能与奥氏体化温度之间的关系,探讨了这种铸钢的强韧化耐机制。试验结果表明,新型贝氏体铸钢具有优异的综合力学性能和高的耐磨性,是一种很好的抗磨材料。     

Evaluation of Mechanical Properties According to Nb Content of High Strength Steel Manufactured in VIM

As the aircraft and aerospace industry and the automobile industry are developed, the demand of reliable materials with high strength and high toughness is steadily increased. The grain miniature method which improves the ductility and the toughness simultaneously under high strength is the miniature of the casting microstructure. In this paper, the Nb which affects the austenite grain miniature is added by 0.00%, 0.03% and 0.06% in this steel and the ingot is manufactured in a vacuum induction melting furnace （VIM）. The casting microstructure and the mechanical property of the maraging steel according to Nb contents are analyzed by conducting the solution annealing and the age hardening after hot rolling. In this result, a specimen containing 0.03% Nb is most miniature. When it does the long time age hardening, the precipitation estimated as the carbide is appeared. The mechanical properties are excellent if a specimen containing 0.06% Nb does the age hardening during 8 h in 482℃.     

热处理工艺对连铸10CrNi3MoV钢性能的影响

针对高温热成型及正常调质处理后连铸10CrNi3MoV钢性能恶化这一问题,研究了循环/亚温淬火热处理工艺,进行了力学性能测试、显微组织观察及晶粒度评定.结果表明,采用亚温淬火( 835℃×2h+ 820℃×2h)+高温回火(630℃×3h)热处理工艺,可有效细化连铸10CrNi3MoV钢的晶粒,显著改善其低温韧性,使其...     

增材制造铜/钢双金属材料研究进展

铜/钢双金属材料具有力学强度高、物理化学性能优良等优势,在交通运输、电力能源和建筑工业等领域应用前景广阔。然而,传统熔铸工艺在制造铜/钢双金属材料时,容易在铜/钢界面处产生偏析现象,在一定程度上限制了铜/钢双金属材料的发展。与传统工艺相比,增材制造技术不仅能实现复杂加工零件的快速制造,而且在成形过程中较短的保温时间能缓和或消除异种金属材料界面产生的冶金缺陷,进而增强铜/钢双金属材料的力学性能。由于双金属材料是近年来的研究热点,有关增材制造铜/钢双金属材料的综述性文章较少,故综述了近年来激光、电子束及电弧增材制造技术制造铜/钢双金属材料的研究发展现状,分析了各技术的优缺点,并从制备方法、工艺参数及界面合金元素等角度,分析了影响材料界面组织性能变化的关键因素。发现在增材制造铜/钢双金属材料方面,目前激光增材制造技术主要应用于精度要求较高的小尺寸零部件,电子束增材制造技术适用于某些具有特殊性能的合金,如钛合金,而电弧增材制造技术适用于精度要求较低的大型复杂零部件。在铜/钢双金属材料增材制造过程中,界面处易形成显微组织分布不均匀、界面晶粒尺寸差异较大等现象,导致界面处产生应力集中,从而造成材料...     

薄带连铸含磷低碳钢的组织性能研究

介绍了国内外在薄带连铸含磷低碳钢组织性能方面的研究进展.双辊薄带连铸的生产方式在一定程度上能提高固溶在基体中的磷含量,减小钢中磷在晶界上的偏析,对力学特性没有负面影响.指出采用双辊薄带连铸工艺来尝试含高磷薄规格耐大气腐蚀钢种的开发是一个具有工业化应用前景的方向.     

钢主梁拱桥组合桥面系力学性能分析

钢-混凝土组合结构桥面系近几年开始在拱桥结构中使用,拱桥中组合桥面系受力复杂,其力学性能受钢与混凝土是否连接、是否张拉系杆以及混凝土的浇注顺序等影响。该文采用空间有限元模型,开展了钢主梁拱桥组合桥面系的力学性能研究。研究表明:在钢主梁拱桥结构中混凝土桥面板与钢主梁是否结合对桥面系的整体受力影响甚微,只对桥面系局部位置的混凝土桥面板应力分布有所影响;拱桥中是否安装系杆对桥面系的受力影响较大,而且桥面系的受力与系杆张拉力有密切关系;对于组合桥面系的拱桥采用一次浇筑混凝土桥面板施工方法的桥面系受力要明显优于采用分段浇筑混凝土桥面板的方法。     

超高强度马氏体时效钢研究进展

马氏体时效钢是一类特殊的超高强度钢,主要依靠在超低碳铁镍马氏体基体上析出金属间化合物沉淀相进行强化,具有非常优异的综合力学性能与加工工艺性能,在航空航天、机械制造、原子能和军事等领域得到了广泛应用.综述了马氏体时效钢的发展历史,针对其良好的强韧性匹配,从合金化、组织结构、力学性能等方面概述了马氏体时效钢当前的研究现状,...     

一种低合金铸钢力学性能尺寸效应的探讨

分别用同炉浇注的基尔试块，长方体试块和铸件本体上取样检测的力学性能，探讨一种低合金铸钢力学性能的尺寸效应，对从长方体试块上取们检测学性能的判据进行了评定。     

Effect of Ni Contents on the Microstructure and Mechanical Properties of Martensitic Stainless Steel Guide Roll by Centrifugal Casting

A novel process based on centrifugal casting was developed to produce martensitic stainless steel for guideroll materials. Centrifugal casting provides a lower production cost and less of the thermal cracking defects which normally occur in the overlaid welding process. In this study, the effects of Ni on the microstructure and mechanical properties of martensitic stainless steel were investigated. The results show that the addition of Ni resulted in a decrease in the volume fraction of delta ferrite and an increase in the volume fraction of the retained austenite, respectively. Moreover, a tensile strength of 1600 MPa with an elongation of 4% were obtained after tempering at 500℃ for 2 h. These values were higher than those obtained by using the conventional overlaid process.     

新型低镍铸造不锈钢的组织及其磨蚀行为研究

设计了新型低镍铸造不锈钢的化学成分，研究了该钢的组织及其腐蚀与磨蚀行为。结果表明，具有双相组织的新型铸造不锈钢，在含有固相颗粒的高温碱介质中具有良好的耐腐蚀与耐磨蚀性能，此外，该钢还具有较好的力学性能和铸造性能，且成本较低。具有广阔的工业应用前景。     

ZG 1Mn19Ni3Al 铸焊结构低温性能研究

通过化学成分设计和金相组织设计，开发了一种适用于与１６Ｍｎ钢组成铸焊结构的新铸钢ＺＧ１Ｍｎ１９Ｎｉ３Ａｌ。研究了这两种材料组成的焊板在常温、低温（－１９６℃）下的力学性能和冲击断口形貌。试验结果表明，夹杂物和焊接线能量对其低温冲击韧性有着显著的影响。具有γ＋ε双相组织的ＺＧ１Ｍｎ１９Ｎｉ３Ａｌ钢用于低温（－１９６℃）铸焊结构中时要注意钢水精炼和采用适当的焊接线能量     

Experimental investigation on heat treatment of a high‐speed steel for hot rolling roll mill

The authors describe the researching results to optimise the hardening and tempering of the high carbon high‐speed steel for rolls containing 2.38%C, 5.07%V, 6.34%Mo, 5.09%Cr, 1.20%Ni, 1.17%Nb, 0.09%Ti and 0.05%RE by means of light optical microscope (LOM), scanning electron microscope (SEM), backscattered electron image (BSE), X‐ray diffraction (XRD), and hardness, tensile strength, impact toughness and wear testers. The results show that the microstructure of above casting high‐speed steel is given by a tempered martensitic matrix surrounded by eutectic carbides. Casting high‐speed steel has higher hardness quenching at 1280 K–1340 K, and it has higher hardness, tensile strength, impact toughness, and abrasive wear resistance tempering at 793 K–833 K. The comprehensive properties of casting high‐speed steel is the best while air‐cooling quenching about 1340 K and tempering about 813 K.     

TiO_2对挤压铸造Al_2O_(3p)/钢基复合材料组织与力学性能的影响

在预制坯中加入TiO_2粉末,利用挤压铸造法制备Al_2O_3颗粒增强1065钢基复合材料,研究TiO_2对复合材料组织与力学性能的影响。结果表明:TiO_2使基体与Al_2O_3的结合界面形成了TiO_2、Al_2TiO_5界面层;添加TiO_2的复合材料硬度和三点弯曲强度分别为39.0HRC,743.94MPa,比未添加TiO_2的复合材料分别提高了10.0%,26.4%;断口扫描表明,添加TiO_2的复合材料界面结合良好无裂纹,Al_2O_3颗粒表现为穿晶断裂。说明加入的TiO_2改善了Al_2O_(3p)/钢基复合材料界面结合强度,提高了复合材料力学性能。     

An integrated formulation for hierarchical cast design problems in the steel making industry

Production design is a key decision problem of steel making industry but due to its complexity, solution properties are not well understood. The design problem can be viewed as a multi-stage problem of bin packing, matching and sequencing sub-problems. Traditionally a sequential approach which treats each sub-problem separately has been applied to the simple case where mould width change is not allowed. However, for more general cases where casting with width change and different width is allowed, the sequential approach fails to generate good solutions. In this paper, we propose a mathematical programming formulation which can solve the design problem in an integrative way. By introducing multi-layer network representation of the cast design problem, it is now possible to generate an integrated formulation for the proposed problem. Based on the formulation, we derive a heuristic algorithm. The algorithm is adopted and tested at a large international integrated steel mill. The computational tests with real data-sets show that the proposed algorithm is quite effective and practical.     

Gefüge und mechanische Eigenschaften eines durch Sprühkompaktieren hergestellten Stahles 100Cr6

Microstructure and mechanical properties of a high strength bearing steel SAE 52100 produced by spray deposition Spray depositing allows the production of steels having a structure which is free of any macro‐segregation, homogeneous and equiaxed. Nevertheless the spray deposition of steels shows some effects that have to be regarded as disadvantages. A porous region at the billet border and a rather coarse‐grained microstructure can be noticed. As a result, in the presented work the influence of a subsequent hot rolling and a following heat treatment on microstructure and mechanical properties has been investigated. For this purpose the bearing steel SAE 52100 has been used as master material. The initial microstructure has been transformed to a homogeneous equiaxed fine‐grained pearlitic microstructure without any remaining porosity. To get use of the characteristic properties of this high‐strength steel an isothermal bainitic hardening has been carried out. Information about the mechanical properties of this material has been gained by tensile and fatigue tests. For fatigue tests in the longitudinal and cross direction of the hot rolled bars a special miniature specimen has been developed.     

取向硅钢制备工艺及其发展趋势

取向硅钢作为一种重要的铁芯材料,在电力行业中有着广泛的应用.基于生产工艺及技术特点,取向硅钢的制备工艺可以分为传统厚板坯工艺、薄板坯连铸连轧工艺及双辊薄带连铸工艺.传统的厚板坯工艺是工业生产取向硅钢的主要方法,其按加热温度又可分为板坯高温加热、板坯中温加热以及板坯低温加热工艺,其中板坯低温加热工艺具有加热温度低、能耗少...     

TMF criteria for Lost Foam Casting aluminum alloys

The purpose of this paper is to define a thermo‐mechanical fatigue criterion in order to predict the failure of aluminum alloys components issued with the lost foam casting process and used in particular in the automotive industry. The microstructure of the studied materials (A356–A319 aluminum alloys) is clearly affected by the lost foam casting process which can directly affect the mechanical properties, the damage mechanisms and the fatigue failure of specimens and components. The major problem in defining a predictive fatigue criterion in this case is the fact that it should be applicable for the component which is submitted to complex multiaxial thermo‐mechanical loadings. Since many years, energy‐based criteria have been used to predict fatigue failure of this class of materials. Then, different energy‐based criteria are tested in order to take into account different types of triaxiality and mean stress effects corrections. The fatigue lifetime results predicted by both of them show a good agreement with experimental results.     

Influence of austempering temperature on the mechanical properties of a low carbon low alloy steel

In this investigation, a new low alloy and low carbon steel with exceptionally high strength and high fracture toughness has been developed. The effect of austempering temperature on the microstructure and mechanical properties of this new steel was examined. The influence of the microstructure on the mechanical properties and the fracture toughness of this steel was also studied.Test results show that the austempering produces a unique microstructure consisting of bainitic ferrite and austenite in this steel. There were significant improvement in mechanical properties and fracture toughness as a result of austempering heat treatments. The mechanical properties as well as the fracture toughness were found to decrease as the austempering temperature increases. On the other hand, the strain hardening rate of steel increases at higher austempering temperature. A linear relationship was observed between strain hardening exponent and the austenitic carbon content.     

Study in the variation of mechanical properties of nodular cast iron depending upon section thickness

Cast iron has become a popular cast metal material which is widely used in modern industry and today's technology because of its low cost and desirable properties such as good castability, convenient machining properties, better wear resistance, etc. This paper is concerned with the variation of mechanical properties depending on section thickness of nodular cast iron. Firstly manufacturing process of GGG40 (EN‐GJS‐400‐15/DIN 1693 or 60‐40‐18/ASTM A536) nodular (ductile) cast iron was performed. Sand mould casting was only used as a molding process. Following, convenient moulds were prepared and the casting process was carried out in moulds that have different diameters (≤30 mm) to examine the cooling rate effects to the mechanical properties. Finally, tensile, hardness, metallography and fatigue tests were applied to cast materials test specimens. The results show that the cooling rate which is related to the section thickness affects the mechanical properties clearly.     

核电用316L不锈钢粉末增材制造研究现状

增材制造技术是一种无须模具、近净成形的先进制造工艺。不锈钢是一种在核电行业广泛应用的结构材料。实现不锈钢结构件的增材制造将进一步推动增材制造技术的发展,也可为核行业带来革命性改变。以核电用316L不锈钢为例,系统阐述了不锈钢粉末增材制造研究现状,包括粉末制备工艺现状、增材制造成形工艺现状以及成形件的组织性能研究现状。目前,增材制造用316L不锈钢粉末的制备工艺主要为雾化法,粉末的物化性能受制粉工艺参数的影响。在激光粉末床熔融增材制造技术、电子束选区熔化技术和等离子增材制造技术中,尤以激光粉末床熔融增材制造不锈钢的应用最为广泛。增材制造316L不锈钢的组织与性能存在各向异性,但各向异性可通过增材制造的后处理技术消除。目前增材制造最为常用的后处理技术为热处理。与锻造316L不锈钢相比,经热等静压处理的增材制造316L不锈钢的力学性能与辐照性能更优。目前,核用不锈钢的增材制造技术还处于起始阶段,后续应重点关注增材制造的成形机理及成形材料中子辐照性能等内容。